Determination of apomorphine freebase in sublingual tablets by proton nuclear magnetic resonance spectroscopy.

An apomorphine sublingual tablet formulation under development contains mixtures of apomorphine freebase (FB) and apomorphine hydrochloride salt. It is important to have a reliable analytical method to determine the ratio of the base and salt forms to ensure accuracy, reproducibility and robustness of the manufacturing processes as well as to meet the requirements of the quality target product profile. A Proton Nuclear Magnetic Resonance ((1)H NMR) spectroscopy method based on the proton shift of the amine methyl group (N-CH3) in apomorphine has been developed to determine the mole percentage of freebase to the total mole of freebase and hydrochloride salt in the drug product. The method was evaluated in terms of specificity, linearity, and variability. The presence of excipients does not interfere with the analysis. A standard calibration curve of the chemical shift as a function of the proportion of freebase forms of apomorphine was established, covering the range of 100% apomorphine freebase to 100% apomorhine hydrochloride. The correlation coefficient (r(2)), slope, and Y-intercept of the regression line are 0.998, -0.00596, and 3.191, respectively. The day-to-day variability of the (1)H shift in two instruments in the standard is less than 1% RSD. Three lots of the sublingual tablet drug product were examined and quantified by the standard. The mole percent apomorphine freebase was determined to be 73.8%, 75.2%, and 76.2%, respectively, within 100.0%±2.0% of the target value of 75.0%. The method is a new avenue to use the (1)H NMR technique for determination of apomorphine freebase and salt ratio in a solid drug product dosage form for release testing and in-process control.

Analysis of non-covalent aggregation of synthetic hPTH (1-34) by size-exclusion chromatography and the importance of suppression of non-specific interactions for a precise quantitation.

There are few methods available for the rapid and precise quantitation of non-covalent aggregation. Size-exclusion chromatography (SEC), a traditional approach, used to measure the non-covalent aggregation can easily disrupt the weak forces holding an aggregate together. Under the conditions described in this paper the disaggregation of non-covalent aggregate of the synthetic human parathyroid hormone hPTH (1-34) due to hydrophobic/electrostatic interactions with the size-exclusion chromatography column packing was completely suppressed. This report details the effectiveness of adding salts and organic solvents in the mobile phase to overcome non-specific interactions that disrupt the aggregate during the SEC process and may aid in the understanding precise quantitation of non-covalent aggregation.